This invention relates to a method for changing a heated mold at a forming station in a heated chamber where the mold cyclically forms heated glass sheets.
Glass sheets are conventionally formed by heating within a furnace and then forming within a heated chamber prior to delivery for cooling. Such cooling can be slow cooling to provide annealing or faster cooling that provides heat strengthening or tempering. In connection with heating of the glass sheets, see U.S. patent Nos.: U.S. Pat. No. 3,806,312 McMaster et al.; U.S. Pat. No. 3,947,242 McMaster et al.; U.S. Pat. No. 3,994,711 McMaster; U.S. Pat. No. 4,404,011 McMaster; and U.S. Pat. No. 4,512,460 McMaster. In connection with glass sheet forming, see U.S. patent Nos.: U.S. Pat. No. 4,282,026 McMaster et al.; U.S. Pat. No. 4,437,871 McMaster et al.; U.S. Pat. No. 4,575,390 McMaster; U.S. Pat. No. 4,661,141 Nitschke et al.; U.S. Pat. No. 5,004,491 McMaster et al.; and U.S. Pat. No. 5,472,470 Kormanyos et al. In connection with the cooling, see U.S. patent Nos.: U.S. Pat. No. 3,936,291 McMaster; U.S. Pat. No. 4,470,838 McMaster et al.; U.S. Pat. No. 4,525,193 McMaster et al.; U.S. Pat. No. 4,946,491 Barr; and U.S. Pat. No. 5,385,786 Shetterly et al.
During the forming process, the heated glass sheets can be supported by a vacuum generated at a downwardly facing mold whose initial support of the glass sheet upon being received from a heating conveyor can be assisted by an upwardly directed heated gas flow that can be provided by gas jet pumps, such as disclosed by U.S. Pat. No. 4,204,854 McMaster et al. and U.S. Pat. No. 4,222,763 McMaster.
For effective high yield glass sheet forming, it is important for cooperable molds to be properly positioned upon mounting and aligned with each other during each cycle of operation therebetween, which is made more difficult due to the heated environment in which the glass sheet forming takes place. See, U.S. patents: U.S. Pat. No. 4,781,745 Mumford; U.S. Pat. No. 5,158,592 Buckingham; U.S. Pat. No. 5,092,916 McMaster; and U.S. Pat. No. 5,230,728 McMaster. The heated environment also makes it more difficult to change molds between different production runs that cannot utilize the same molds. See U.S. Pat. No. 5,137,561 Schnabel, Jr. which discloses changing a cloth ring on a glass sheet heating furnace.
After forming, heat strengthening or tempering can be performed by rapid cooling at a quench section between lower and upper quench modules thereof and may have provision for transferring the glass sheet during such cooling by blowing a greater amount of gas upwardly so as to permit the associated quench ring that carries the glass sheet to move back to the heated forming station in preparation for the next cycle. See U.S. Pat. No. 4,361,432 McMaster et al.
All of the above cited patents are hereby incorporated by reference.
An object of the present invention is to provide an improved method for changing a heated mold at a forming station in a heated chamber where the mold cyclically forms heated glass sheets.
In carrying out the above object, the mold changing method is performed by moving an unloading cart on a primary railway along a direction of conveyance of the heated chamber from an unloading station through a switching station and then to the forming station to receive the heated mold. Thereafter, the unloading cart is moved with the heated mold thereon along the primary railway from the forming station through the switching station to the unloading station. Subsequently, a loading cart with a second heated mold thereon is moved on an auxiliary railway laterally with respect to the direction of conveyance from a mold preheating station to the switching station and then on the primary railway along the direction of conveyance to the forming station for loading of the second heated mold at the forming station.
A mold support assembly is preferably moved downwardly in the forming station to disengage mold mounts thereof from the first mentioned heated mold prior to the movement thereof on the unloading cart from the forming station. The mold support assembly is moved upwardly to engage the mold mounts thereof with the second heated mold after movement thereof on the loading cart to the forming station.
The first mentioned heated mold and another heated mold detachably connected thereto are initially moved on the unloading cart out of the heated chamber. Thereafter, the second heated mold and a further heated mold detachably connected to the second heated mold are moved on the loading cart into the heated chamber for installation and are then disconnected from each other for the cyclical glass sheet forming.
The objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.